In radiation imaging, collimators are used to limit the passage of radiation beams to a specific angle in order to minimize detection of beams of scattered or secondary radiation. Single angle collimation provides 2-dimensional (2D) projection of radiation sources on an imager while the combining of multi angle projections provides 3-dimensional (3D) position of radiation sources by image reconstruction techniques. Hence, it is more desirable to achieve 3D images particularly in clinical nuclear imaging. Devices have been proposed for multi angle projection imagers using multiple detectors at different positions, or by moving the position of a single detector, or by fixing the location of a detector and using multiple collimators each of which has a different collimation angle. It is not always feasible to combine aspects of these methods due to physical interference with the imaging target. Previously proposed multi angle collimators typically include either variable angle slant hole (VASH) collimators or multi-view collimators.
Although the VASH provides an adjustable angle of collimation, the reported alignment mechanism of the multiple leaves clearly does not provide accurate alignment of each leaf, thereby resulting in a reduced size of the openings and an inaccurate collimation angle that reduces the output image quality.
Accordingly, it would be desirable to provide a multiple leaf collimator in which the openings are accurately aligned, that maintains a constant collimation angle, and thus achieves high output image quality.